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authorAnton Arapov <anton@redhat.com>2012-06-08 12:58:00 +0200
committerAnton Arapov <anton@redhat.com>2012-06-08 12:58:00 +0200
commit6792a3f47a2e42d7164292bf7f1a55cfc4c91652 (patch)
treeb90c002bfbbeaec92f5d8a2383dcabf6524016f7 /arch/hexagon/include/asm/cmpxchg.h
parentfe2895d3d55146cac65b273c0f83e2c7e543cd0e (diff)
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fedora kernel: b920e9b748c595f970bf80ede7832d39f8d567dav3.4.1-2
Signed-off-by: Anton Arapov <anton@redhat.com>
Diffstat (limited to 'arch/hexagon/include/asm/cmpxchg.h')
-rw-r--r--arch/hexagon/include/asm/cmpxchg.h90
1 files changed, 90 insertions, 0 deletions
diff --git a/arch/hexagon/include/asm/cmpxchg.h b/arch/hexagon/include/asm/cmpxchg.h
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+++ b/arch/hexagon/include/asm/cmpxchg.h
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+/*
+ * xchg/cmpxchg operations for the Hexagon architecture
+ *
+ * Copyright (c) 2010-2011, Code Aurora Forum. All rights reserved.
+ *
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+#ifndef _ASM_CMPXCHG_H
+#define _ASM_CMPXCHG_H
+
+/*
+ * __xchg - atomically exchange a register and a memory location
+ * @x: value to swap
+ * @ptr: pointer to memory
+ * @size: size of the value
+ *
+ * Only 4 bytes supported currently.
+ *
+ * Note: there was an errata for V2 about .new's and memw_locked.
+ *
+ */
+static inline unsigned long __xchg(unsigned long x, volatile void *ptr,
+ int size)
+{
+ unsigned long retval;
+
+ /* Can't seem to use printk or panic here, so just stop */
+ if (size != 4) do { asm volatile("brkpt;\n"); } while (1);
+
+ __asm__ __volatile__ (
+ "1: %0 = memw_locked(%1);\n" /* load into retval */
+ " memw_locked(%1,P0) = %2;\n" /* store into memory */
+ " if !P0 jump 1b;\n"
+ : "=&r" (retval)
+ : "r" (ptr), "r" (x)
+ : "memory", "p0"
+ );
+ return retval;
+}
+
+/*
+ * Atomically swap the contents of a register with memory. Should be atomic
+ * between multiple CPU's and within interrupts on the same CPU.
+ */
+#define xchg(ptr, v) ((__typeof__(*(ptr)))__xchg((unsigned long)(v), (ptr), \
+ sizeof(*(ptr))))
+
+/*
+ * see rt-mutex-design.txt; cmpxchg supposedly checks if *ptr == A and swaps.
+ * looks just like atomic_cmpxchg on our arch currently with a bunch of
+ * variable casting.
+ */
+#define __HAVE_ARCH_CMPXCHG 1
+
+#define cmpxchg(ptr, old, new) \
+({ \
+ __typeof__(ptr) __ptr = (ptr); \
+ __typeof__(*(ptr)) __old = (old); \
+ __typeof__(*(ptr)) __new = (new); \
+ __typeof__(*(ptr)) __oldval = 0; \
+ \
+ asm volatile( \
+ "1: %0 = memw_locked(%1);\n" \
+ " { P0 = cmp.eq(%0,%2);\n" \
+ " if (!P0.new) jump:nt 2f; }\n" \
+ " memw_locked(%1,p0) = %3;\n" \
+ " if (!P0) jump 1b;\n" \
+ "2:\n" \
+ : "=&r" (__oldval) \
+ : "r" (__ptr), "r" (__old), "r" (__new) \
+ : "memory", "p0" \
+ ); \
+ __oldval; \
+})
+
+#endif /* _ASM_CMPXCHG_H */